Fujitsu Corporation

Yasuo Kousaki

Masashi Asakawa

Noriyuki Matsui

Shinichiro Uekusa

Tendo Hirai

Shigeru Takamura

Method includes specifying a first relationship between power supply voltage in a semiconductor device and the maximum operable frequency of internal circuit upon fluctuation of the power supply voltage being detected by changing the power supply voltage in the semiconductor device and the operating frequency of the internal circuit, specifying second relationship between the maximum operable frequency of the internal circuit and the mounting manner of the decoupling capacitor upon the fluctuation of the power supply voltage being detected by changing the mounting manner of the decoupling capacitor and the operating frequency of the internal circuit, and calculating the fluctuation amount of the power supply voltage corresponding to the decoupling capacitor mounting manner based on the first relationship and the second relationship.

Method and system for voltage fluctuation amount calculation

An SSO noise calculating unit estimates the amount of simultaneously operating signal noise caused by simultaneous operations of input/output pins peripheral to a power supply voltage pin as a center. A PLL jitter calculating unit estimates the amount of jitter occurring at the power supply voltage pin by using as an input the estimated amount of simultaneously operating signal noise, and by referencing a correlation between the amount of simultaneously operating signal noise and the amount of jitter, which indicates a correlation calculated beforehand between the amount of simultaneously operating signal noise and the amount of jitter.

Jitter amount estimating method, method for calculating correlation between amount of simultaneously operating signal noise and jitter amount, and recording medium

In an initial stage of device design, a circuit analysis control unit of an evaluation board stores SSO noise basic characteristic data actually measured by the evaluation board in an SSO noise basic characteristic data storage unit, and an SSO noise calculation unit calculates a rough amount of SSO noise on the basis of the SSO noise basic characteristic data. After a noise check is OR, the design proceeds, and a PCB parameter is determined, a circuit analysis control unit acquires the SSO noise basic characteristic data according to actual device PCB design information, and corrects the SSO noise basic characteristic data in the SSO noise basic characteristic data storage unit. Then, the SSO noise calculation unit performs a detailed analysis of an amount of SSO noise using the corrected SSO noise basic characteristic data.

Method for acquiring basic characteristic of simultaneous switching noise in method for estimating simultaneous switching noise on semiconductor device

A memory array is divided into a plurality of blocks. A plurality of mode storage units is so disposed as to correspond to the memory blocks. When a plurality of controllers outputs a mode setting instruction at the time of making of power, a setting unitsets control information designated by the mode setting instruction to the corresponding mode storage unit. When different controllers gain access to a synchronous DRAM, an access operation is executed for the corresponding memory block in accordance with the control information.

Synchronous DRAM utilizable as shared memory

A circuit that prevents illegal transformation of data in a non-volatile memory comprises a three circuits which generate three reference currents of different amplitude, there comparison circuits which respectively compare the three reference currents with a cell current, a writing/deletion circuit which writes data in or deletes data from the cells. A control circuit is provided which outputs a corresponding information based on the result of comparison by the comparison circuit, and makes said writing/deletion circuit execute writing data in or deletion of data from a target cell once more when the cell current is greater than the second reference current or the cell current is not greater than the third reference current.

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Kawasaki, Japan

Yasuo Kousaki